1. Field of the Invention
The present invention relates, in general, to a mechanical expander for tubing for heat transfer products.
2. Information Disclosure Statement
A preliminary patentability search in class 72, subclass 393, disclosed the following patents which may relate to the present invention: Brinen, U.S. Pat. No. 2,480,629 issued Aug. 30, 1949; Richter, U.S. Pat. No. 3,358,492 issued Dec. 19, 1967; Hess et al., U.S. Pat. No. 3,981,172 issued Sept. 21, 1976; Rabe, U.S. Pat. No. 4,779,445 issued Oct. 25, 1988; and Paterick, U.S. Pat. No. 4,821,391 issued Apr. 18, 1989 may relate to the present invention.
Brinen discloses a hand held tool for beading and flaring the ends of metal tubes into a header plate.
Richter discloses an expandable mandrel for expanding a tubular member. The mandrel automatically retracts as the rod is initially passed through the bore of a tube, and which mandrel automatically expands to effect the expansion of the tube on reversing of the direction of the mandrel through the tube to be expanded.
Hess et al. discloses a method and apparatus for expanding long lengths of large diameter spirally wound and helically welded pipe. The apparatus includes a radially expandable die head assembly for incrementally expanding the pipe advanced over the die head and wherein the die head has a helical groove which corresponds to the helical weld seam of the pipe.
Rabe discloses an elongated tool device for use in installing a tubular sleeve within a tube and forming a pressure-tight seal therebetween. The tool device contains dual internal pistons which are pressurized in sequence to expand collet fingers radially into the close-fitting sleeve and provide a leak-tight seal between the sleeve and surrounding tube.
Paterick discloses an apparatus for forming a muffler mechanical lock joint, and the resulting assembly. The apparatus includes a punch, a wedge, a drive, and a return means. The punch is radially expandable and provides for deforming a flange and tube of muffler components into a mechanical lock joint, while the punch is radially expanded. The wedge is axially movable, and wedges the punch into radial expansion when axially moved.
Applicant has knowledge of expanders of the so-called pinch-roller or slip drive type wherein rods are used to expand tubes. The slip drive type expander utilizes pairs of oppositely turning rollers that drive the rods longitudinally. With the use of such slip drive expanders the rollers pinch the rods causing the rods to wear out. Also the rods break and must be hardened. Thus, the pinch-roller type of machine is expensive to maintain.
Also, applicant has knowledge of vertically oriented expanders having a large cylinder with the piston rod thereof attached to a plate to which in turn is attached a plurality of rods. Although particularly suitable for high production for the expansion of tubing of heat transfer coils having the same center-to-center spacing of the tubes, such vertically oriented expanders cannot be quickly changed from heat transfer coils having one particular center-to-center dimension of the tubes to another. Also, such vertically oriented expanders are not suitable for expanding U or hair-pin tubes because there is the problem of the rods damaging the tubes by projecting through the end of the U turn in the tubes.
In addition, applicant has knowledge of hand held expanders which are slow in operation and unwieldy to handle, particularly if long rods are utilized.